Christian Tarsney

I describe a thought experiment in which an agent must choose between suffering a greater pain in the past or a lesser pain in the future. This case demonstrates that the ‘temporal value asymmetry’ – our disposition to attribute greater significance to future pleasures and pains than to past – can have consequences for the rationality of actions as well as attitudes. This fact, I argue, blocks attempts to vindicate the temporal value asymmetry as a useful heuristic tied to the asymmetry of causation. Since the two standard arguments for the rationality of the temporal value asymmetry appeal to causal asymmetry and the passage of time respectively, the failure of the causal asymmetry explanation suggests that the B-theory, which rejects temporal passage, has substantial revisionary implications concerning our attitudes toward past and future experience.

I argue that the use of a social discount rate to assess the consequences of climate policy is unhelpful and misleading. I consider two lines of justification for discounting: (i) ethical arguments for a "pure rate of time preference" and (ii) economic arguments that take time as a proxy for economic growth and the diminishing marginal utility of consumption. In both cases I conclude that, given the long time horizons, distinctive uncertainties, and particular costs and benefits at stake in the climate context, discount rates are at best a poor proxy for the normative considerations they are meant to represent.